The preceding paragraph is from the middle of a 読み物 in the textbook I am using. The only questions I had were on the two sentences at the end highlighted in red. The rest is for context.

Question 1: As for the sentence [マクドナルドは、アメリカ人としては日本で始めての英語教師となり、この十二人の侍に英語を教えたが、翌１８４９年四月に長崎へやってきたアメリカの軍艦で北アメリカへ送り返された] I know I should probably know better than to second-guess particles, but I don't know why とfollows 英語教師.
Would [マクドナルドは、アメリカ人としては日本で始めての英語教師になり、この十二人の侍に英語を教えたが、翌１８４９年四月に長崎へやってきたアメリカの軍艦で北アメリカへ送り返された] mean the same thing, or something different?

Question 2: As for the sentence [彼は一生日本のことが忘れられなかったらしく、１８９４年にワシントン州の姪の家で病死した時、姪に「サヨナラ、マイ・ディア、サヨナラ」と言って死んだと言われている], is らしく a form of らしい (the らしい used in the sense of "to appear", or "to seem")?

と is very often used with なる in written Japanese, it equal to に. There might be some nuances, but the most important I think is that と is used in written Japanese.

らしく is らしい. You are probably used to らしくて for linking sentences, but again, this is a case of more written style, and it is normal to not use て but the stem. You see that in your first question as well, となり, is same as となって/になって.
Also here there are some nuances, but again I think at first it is good enough to know that らしく is a more written style than らしくて.

I agree with the above posters about those sentences. I just wanted to add, regarding らしく , in Japanese you don't tend to report what people think and feel as if you have direct access to their feelings. Instead you have to qualify it, so in nonfiction it's very typical to say it seems that MacDonald never forgot Japan, rather than to just say straight-out that he never forgot Japan.
It's similar to how you can only use the -tai form for talking about yourself, not talking about other people.

NocturnalOcean wrote:と is very often used with なる in written Japanese, it equal to に. There might be some nuances, but the most important I think is that と is used in written Japanese.

らしく is らしい. You are probably used to らしくて for linking sentences, but again, this is a case of more written style, and it is normal to not use て but the stem. You see that in your first question as well, となり, is same as となって/になって.
Also here there are some nuances, but again I think at first it is good enough to know that らしく is a more written style than らしくて.

Now I know. I'll keep an eye out for となる in written Japanese, and what you pointed out about らしくas well. Thanks for the info.

Far be it from me to correct a native speaker, but I can't say this is a sound explanation.

"と" in the sentence is a particle that refers to the result of an action, influence, etc., and in this case the result is 英語教師 and the action is なる. Certainly "に" also has a very similar usage, and there is a slight difference in nuance. But I don't think と gives a stronger sense of "eventually" and the like.

In general, に of this kind indicates that the attached noun is the result of the following verb, and usually the speaker is only focusing on the result. と in question also works in a similar way, but the focus is on "showing the result to the listener," i.e., you use と when you are like "Hey, this is the result!" while に is used when you simply put the result in a sentence.

For example, 彼は名前をXに改めた is just stating the fact that he changed his name to X while 彼は名前をXと改めた has a sense of "X. That's his new name."

So, マクドナルドは、アメリカ人としては日本で始めての英語教師となり、has kind of emphasis on "the first ever English teacher," and the writer thinks the fact that he started working as "an English teacher" is important. If you swap と with に, it would only state the fact that he started working as Japan's first English teacher from the US.

I'd love to know what NileCat and other native/near-native Japanese speakers think of these pairs:

とうとう最終日になった vs. とうとう最終日となった (I think the latter can have a "You know what? It's the final day." kind of nuance.)
一丸になって戦おう vs. 一丸となって戦おう (The latter is more dramatic because it's clearer that the speaker wants to encourage peers; と is there to emphasize that he wants to tell something to the listener.)
明日を決戦の日に決める vs. 明日を決戦の日と決める (The latter sounds like the speaker (or someone who determined D-day) is a determined person, doesn't it?)

By the way, this explanation and examples are taken from 明鏡国語辞典. It's a small J-J dictionary for native speakers, but it has tons of information about word usage, differences in nuance between synonyms, confusing kanji readings, and many other things learners often get tripped up by. You can also find explanations for other confusing と vs. に things such as "What's the difference between 彼女とキスとする and 彼女にキスをする?" "Is there a difference between ここで先生と会う and ここで先生に会う?" "Why can't I say 父は子に似ている while 父は子と似ている is ok??" and so on.

And, no. This is not viral marketing or anything.

Before you criticize someone, walk a mile in their shoes. That way when you criticize them, you are a mile away and you have their shoes.

Far be it from me to correct a native speaker, but I can't say this is a sound explanation.

"と" in the sentence is a particle that refers to the result of an action, influence, etc., and in this case the result is 英語教師 and the action is なる. Certainly "に" also has a very similar usage, and there is a slight difference in nuance. But I don't think と gives a stronger sense of "eventually" and the like.

蛹になって蝶となる

「～となる」has a nuance something related to time-line. Something happens at the end of the time-line is mentioned using "となる" instead of "になる".
In the example sentence,「マクドナルドは、アメリカ人としては日本で始めての英語教師となり」can be read as emphasis of "He eventually became the first English teacher". It's only a matter of interpretation. I think your explanation is plausible too, though.

とうとう最終日になった vs. とうとう最終日となった
Time-line, again. The former refers to the simple fact that it is the final day. The latter has the nuance that we finally face the day. (Of course the word とうとう has the meaning though)
(I don't understand properly the English nuance of "You know what?" though, it seems a bit different from our intention when we use this expression.)

一丸になって戦おう vs. 一丸となって戦おう
We usually prefer the latter. The former sounds a bit poor.
The important thing in the message is the effort to tie up. Not the act itself. And the effort takes some time.

明日を決戦の日に決める vs. 明日を決戦の日と決める
I agree with you. And it's different from "となる".

NileCat wrote:
(I don't understand properly the English nuance of "You know what?" though, it seems a bit different from our intention when we use this expression.)

To me, "You know what?" has different meanings based on context and tone of voice. "You know what? This is the last day." That could mean that the person has just realized it's the last day. I think it often introduces known information and then offers some additional comment, like "You know what? This is the last day. We don't have to work this hard." or "You know what? We still have five hours left. We could finish the whole project today." But it can also just remark on new, surprising information (I guess I find that hard with the "this is the last day" because most of the time people would know that beforehand.)

10 meanings of と as 格助詞 are listed, and it's the fifth one. I thought this explanation was spot on, and my intuition does support it. I think some usages of と as 接続助詞 have a sort of "time-line" sense as in 国境の長いトンネルを抜けると雪国であった。(by 川端康成) and 夏休みになると海に行ったものだった. But they're not related to に.

With that said, what native speakers have in their minds is always true in the sense that that's the definition of language. I don't like prescriptive grammar either, though I understand it's a useful tool to learn a language. If you still think the difference lies in "time-line," then probably that's the Japanese language you speak as a native speaker. No one can say it's wrong.

As for "You know what?", I think Yudan Taiteki already gave a solid explanation. But here is my understanding:

Reading NileCat's posts, it seems this と vs. に thing is so subtle different dictionaries explain it differently, and native speakers' intuitions are not consistent. Perhaps it's a regional thing. Or maybe that's because the younger generation speaks slightly different Japanese. I'm of the opinion that, as Meikyo Japanese Dictionary says, the difference is that "と" is used to present information the particle is attached to (Note: と has a lot of meanings, so this is not always the case.). NileCat thinks the と in question indicates a certain time-line sense, which Daijirin confirms.

Daijirin is a reliable J-J dictionary designed for adult native Japanese speakers. My intuition doesn't match its definition of と in question, but it's definitely a great monolingual dictionary, and I do recommend it to advanced Japanese learners.

I apologize if this discussion has caused confusion among some of the members of this forum. I think this topic is very interesting in that even popular J-J dictionaries for native speakers don't agree with each other. I'm pretty sure there are a lot of fluent Japanese speakers here, and would like to know what they think of the difference between と and に in this case.

It seems either is valid when it comes to this と vs. に explanations, but here is my "rebuttal" to the point NileCat made in his last post aka a shameless attempt to convert him:

Take this example 朝からずーっと、今日中に彼女に聞かなくちゃって思ってたんだけど、結局明日になっちゃった… Obviously this sentence has the time-line sense you're talking about. The speaker has been meaning to ask her, but he failed; morning, noon, evening, ...hey, it's too late! Do I ask her that tomorrow? This sentence doesn't use と, but apparently it carries the eventually-ish sense pretty well.

So, can I say, "朝からずーっと、今日中に彼女に聞かなくちゃって思ってたんだけど、結局明日となっちゃった…"? I'd say it's less frequent. 結局明日になる and 結局明日となる are both grammatical and sound natural. Is this because of the formality thing another poster mentioned? Maybe. But it seems to me that と is used more often in a formal situation because in formal speech/writing, the speaker/writer tends to focus on "bringing information" to the audience. My J-J dictionaries don't say と is more formal either.

I'm under the impression that the reason I wouldn't say 結局明日となっちゃった… as often in that context is that I'm feeling guilty about procrastination, i.e., I don't want to bring that up. Now if you say

今日中に聞かなくてはと思っていたが、結局明日となってしまった。

it sounds to me that you're more honest than a person who says

今日中に聞かなくてはと思っていたが、結局明日になってしまった。

because I think the former has more a "bringing this up" kind of nuance.